This invention relates in general to tire changing equipment, and more particularly to a machine for installing giant tires on one-piece rims.
Much of the heavy off-the-road transport equipment, such as the tractors and the trucks used at mines and quarries or the large machines used for earth excavations, utilize so-called giant tires which are large pneumatic tires of the tubeless variety. These tires may range up to 9 feet in diameter and when mounted on their rims weigh over a ton each. The rims alone usually measure in excess of four feet in diameter.
The most common rim for giant tires consists of five basic components which are separable, namely a rim base, a bead seat ring fitted over one side of the rim base, a side flange fitted over the bead seat ring, another side flange fitted over the rim base itself, and a lock ring to hold the bead seat ring in place on the rim base. The five-piece construction enables the rim to be disassembled so that it may be reassembled within a giant tire with relative ease. On the other hand, the multiple components often result in the mismatching of parts on reassembly, and much worse render the mounting quite susceptible to leakage. In this regard, an O-ring must be fitted between the rim base and the bead seat ring to prevent the pressurized air from escaping between the two, but it is not uncommon to have this seal installed improperly or to have it damaged during installation. As a consequence, a slow leak develops, resulting in costly downtime for an expensive piece of equipment.
One-piece rims are now available for installation in giant tires which are manufactued with slight modifications to accommodate such rims. While these rims, which are known as one-piece drop-center rims, eliminate the leakage problems, they present problems of a different character, the most significant of which is the difficulty in mounting. Due to their extreme weight and large size, these tires are extremely difficult to manipulate over the one-piece rims. The problem is compounded by the fact that the side walls of such tires are quite thick and relatively rigid so they are not easily maneuvered over the flanges on the one-piece rims.